1. Field of the Invention
The present invention relates to a safety shutter of a vacuum circuit breaker, and more particularly, to a safety shutter of a vacuum circuit breaker which is mounted on a cradle of a drawable type vacuum circuit breaker and opened or closed when a main body is retracted or pulled out to protect the safety of users from a charging part.
2. Description of the Conventional Art
In general, a vacuum circuit breaker is a circuit breaker installed in a high voltage electric power system to break a circuit to protect the electric power system in the event of a dangerous situation such as a short circuit, an overcurrent, and the like, and it is designed by utilizing excellent insulating performance and arc-extinguishing capability in a vacuum state.
The vacuum circuit breaker is categorized into a drawable type vacuum circuit breaker and a fixed type vacuum circuit breaker. That is, the vacuum circuit breaker is divided into a fixed type circuit breaker which consists only of a main body and is fixed to a switch panel, and a drawable type circuit breaker which is configured to have an outer box called a cradle for facilitating the maintenance and repair of the circuit breaker so that a main body is retracted into or pulled out of the cradle.
FIG. 1 illustrates a cradle 1 of a drawable type vacuum circuit breaker according to the conventional art. The vacuum circuit breaker includes a variety of auxiliary equipment and safety devices. An example of them is a safety shutter 3 located in front of a charging part 2.
The safety shutter 3 of the vacuum circuit breaker is a device that ensures user safety from the charging part 2 by opening or closing the charging part 2 when a main body (not shown) is retracted or pulled out. FIG. 2 illustrates the safety shutter (shutter m assembly) of FIG. 1. The safety shutter according to the conventional art includes an operating lever 4 that receives the pushing force generated by the forward motion of the main body when the main body is retracted, a shutter guide 5 that moves down by the rotation of the operating lever 4, a shutter handle 6 that is turned clockwise or counterclockwise by the movement of the shutter guide 5, a shutter panel 7 that serves to shield the charging part 2, and shutter link 8 that serves as the axis of rotation while supporting the rotation of the shutter panel 7.
The operation of the safety shutter of the vacuum circuit breaker according to the conventional art will be described as follows.
When the main body is retracted into the cradle 1, a protrusion 4a to be brought into contact with the main body is pushed by contact pressure and rotates the operating lever 4 counterclockwise around the coupling axis 4b. The shutter guide 5 connected to the front end of the operating lever 4 moves down, and the shutter guide 5 causes the shutter handle 6 rotatably fixed to a cradle side plate 9 by a shutter handle shaft 6a to rotate. As the shutter handle 6 rotates, the shutter panel 7 rotates to open the charging part 2.
Hereupon, the shutter panel 7 rotates, supported on the shutter link 8. That is, the shutter link 8 acts as the axis of rotation, with one end 8a attached to the cradle side plates 9, and the shutter panel 7 is attached to the other end 8b. Accordingly, the shutter link 8 has a rotation radius setting when the shutter panel 7 attached to the shutter panel 6 rotates. The radius of rotation is the distance between one end 8a and the other end 8b of the link. That is, the rotation of the shutter panel 7 depends on the shutter link 8. However, since the shutter link 8 is fixed, the shutter panel 7 will not move properly and interfere with the charging part 2 or main circuit terminals of the main body in case of any defects or loosening.